ATI Catalyst Tweak Guide

[Page 2] Essential Optimization

This section contains some extremely important optimization information you should read through, understand and perform along with Catalyst tweaking. Do not skip this section.

Windows and System Optimization

Optimization of Windows and your system is critical to the stable, smooth performance of your PC. The place to start is with the TweakGuides Tweaking Companion. It is the complete system optimization guide for Windows users. Designed for novice and advanced users alike, it is written in plain English to help you genuinely understand all aspects of Windows and your PC. The guide covers every major topic, from the correct installation of Windows and critical drivers and software, through to recommendations for every significant setting and feature, all the major performance and convenience tweaks and customizations, as well as detailed troubleshooting advice. There are also links to a range of reliable free applications which can enhance your system and give you viable alternatives to purchasing commercial software. There are separate versions available for Windows XP, Windows Vista and Windows 7.

If you've ever wondered what common graphics and display settings like FPS, VSync, Refresh Rate, Antialiasing and Anisotropic Filtering are, and how they really work, then check out my Gamer's Graphics & Display Settings Guide for all the details in an easy to understand format. The guide also gives you a rundown on exactly how a game goes from a being a set of files on your hard drive to a 3D image on your screen, including relevant performance tips.

Make sure to read the guides above. Even if it takes some time to go through them, you will not only learn how to optimize and troubleshoot any current problems on your system, you will also gain a greater understanding of how your PC and Windows actually work which will really help you in the future. Most if not almost all problems which appear graphics-driver related are actually symptoms of general system instability and lack of optimization. Just because you see a graphics driver-related error message for example, doesn't mean the graphics driver is actually at fault - the error can be caused by a multitude of things such as overclocking, overheating, incorrect or sub-optimal BIOS or Windows settings, etc. Make absolutely certain to go through and optimize Windows before pointing the finger at your drivers or hardware.

Graphics-Specific BIOS Settings

I can't go into all the possible BIOS Settings here, because that would take literally a guide in itself. More importantly, each BIOS is different in many subtle and not-so-subtle ways. I refer readers as always to the Definitive BIOS Optimization Guide. Scroll down that page to find the link to the free version of the guide. If you're serious about making sure your entire BIOS is optimized, and you want to know what all those weird and wonderful settings in your BIOS actually do, make sure you check the guide. Particularly relevant to the topic of this guide are the settings under the 'Graphics Subsystem' section of that guide. Below I provide some easy-to-understand information on the most important video-related BIOS settings and terms:

AGP Port: The Accelerated Graphics Port (AGP) is a dedicated PCI slot for your graphics card. It's the place where some modern graphics cards plug into the motherboard. This port provides the interface between your graphics card and the rest of your system. When people talk about AGP settings, they are essentially referring to settings which affect your graphics card and the speed with which it "talks" to the rest of the system. Some older graphics cards are PCI graphics cards, and some newer graphics cards use PCI-Express (don't confuse the two), and hence don't use the AGP port or the AGP-related settings below. PCI Express is covered further below.

AGP Speed (1x, 2x, 4x, 8x): This setting determines the data transfer rate (speed) of the AGP Bus - the pipeline along which video information flows. As logic suggests, the higher the speed setting, the higher the potential performance of your graphics card. However what is counter-intuitive is the actual performance difference between the various AGP modes. AGP 8x is not twice as fast as AGP 4x, which is not twice as fast as AGP 2x - and so on. The reason for this is that the higher modes provide more bandwidth - that is, the size of the pipeline effectively gets bigger. But if at AGP 4x the pipe is already bigger than the size of the information flowing through it, increasing the pipeline by going to AGP 8x will clearly not make a large difference to speed. Importantly, lowering the AGP speed (e.g. from 8x to 4x) can help improve stability for some systems (especially overclocked ones), and can also resolve some graphics problems. Generally I recommend setting this to the highest available speed in the BIOS, as long as your graphics card also supports that AGP speed. For most systems the performance difference between AGP 4x and AGP 8x is at most around 5-10%.

AGP Aperture Size: This setting determines the allocation of physical RAM for use by an AGP graphics card, should it become necessary. A better description can be found in this AGP Aperture Size FAQ. To decide how big it should be keep in mind the following: (1) keep it above 32MB, as an Aperture Size below 32MB will disable AGP texturing - reducing your performance greatly in games; (2) the greater the amount of Video RAM on your graphics card, the smaller this setting should be; (3) Values between 64MB and 256MB show no real performance difference; and (4) Using larger values can result in more crashes such as General Protection Faults and potential texture corruption. So with all of these in mind, I recommend an Aperture Size of 128MB for most AGP graphics cards. If you have an older 32MB graphics card, set the Aperture to 256MB. If you experience a large number of crashes or texture glitches, try lowering the Aperture to 64MB regardless of your Video RAM amount.

Fast Writes: This setting, whether in the BIOS or in the Catalyst Control Center, is meant to speed up AGP read performance. In practice however it is known in almost all cases to have no noticeable performance impact, and indeed often causes many problems such as crashes and general system instability, especially on overclocked graphics cards. My personal testing has shown it to have literally 0% impact on performance on several different setups. Therefore I strongly recommend disabling Fast Writes in the BIOS (if available) and also disabling it under SmartGart in the ATI Control Panel/ATI Control Center for optimal stability with little or no performance loss.

Sidebanding: This setting controls a method whereby additional new video requests are sent along with the main video information, in effect working alongside the main data channel. This increases bandwidth, which can improve performance, although not by much. In practice Sidebanding can cause instability, particularly on overclocked graphics cards. Sidebanding is usually enabled on most ATI graphics cards, and shouldn't be causing any problems, however if there is a Sidebanding option in your BIOS, and you are experiencing problems, you can try disabling it to see if it helps.

PCI-Express: AGP (see above) is an older interface between your graphics card and the motherboard. PCI Express (PCI-E) is the latest interface which replaces AGP. For a detailed description of it and what it all means, read this excellent PCI Express Overview. In simple terms PCI-E graphics cards work faster and smarter than AGP graphics cards, but you will need both a motherboard with a PCI-E interface and a PCI-E graphics card to take advantage of these improvements. If you are considering upgrading your system, you should seriously consider getting a motherboard with PCI-E and a PCI-E graphics card to maximize performance and provide the potential for future upgradability.

Crossfire: In response to Nvidia's SLI technology, ATI has introduced Crossfire multi-GPU technology. Basically what it does is use two ATI graphics cards to form a single super-card on your system, thereby using both their power to increase your performance. Crossfire differs from SLI technically, because SLI requires driver and game-specific enhancments to make full use of its power, while Crossfire promises performance improvements in all games and 3D applications because of the tiling method it uses. In practice the difference is not necessarily major.

Take the time to undertand and optimize your entire BIOS since incorrect settings in the BIOS will cause problems no matter how much you tweak the software.

Motherboard Drivers

Aside from having the correct BIOS settings, it's very important that you install the latest Motherboard drivers for your system. Many problems such as stuttering or low performance are actually caused by a lack of correct motherboard drivers. These directly affect the level of graphics functionality that is possible on your system, as well as other functionality which indirectly affects graphics performance. See the Driver Installation/Windows Drivers chapter of the TweakGuides Tweaking Companion for more details and download links.

OpenGL and DirectX

DirectX and OpenGL are two major graphics APIs (Application Programming Interfaces) used to develop games and 3D graphics applications on Windows platforms. DirectX is a Microsoft proprietary API, while OpenGL is (as the name suggests) an open standard API. Direct3D (D3D) is a major component of DirectX, and the one most relevant to 3D graphics, hence people often refer to a game as being a Direct3D game. Most games also usually do not have the option of switching between OpenGL or Direct3D mode, and hence you cannot force them to run under another API. Even if they do have such an option, games are usually programmed for optimal performance under one and not the other.

Importantly, you should make sure you're running the latest version of DirectX for maximum compatibility with the latest games. The latest full version of DirectX can be downloaded from here. Windows XP uses DirectX9.0c, while Windows Vista uses a combination of DirectX10 and a different version of DirectX9.0 called DirectX9.0EX, and these are not compatible with Windows XP. Note that DirectX can't be uninstalled as it is a critical system component, so once you've installed the latest official version, if you experience any DirectX-related errors then try doing a re-install of DirectX over your existing install just to be safe. It can't do any harm and it just may resolve the problem.

Power Supply Issues

An often-overlooked aspect of graphics performance and stability is the power supply. Modern graphics cards require a stable source of power, and your Power Supply Unit (PSU) has the main job of providing this to all the components in your system. If you're not using a good PSU, you will have problems running your games with any stability, and you may incorrectly blame Windows or your graphics drivers, or even your games for this. No amount of tweaking will resolve PSU-related problems. Use this Interactive PSU Calculator to see whether your existing PSU's wattage is sufficient. Importantly, keep in mind that stable voltage from the power supply is crucial important, so that needs to be monitored as well - see the BIOS & Hardware Management and Overclocking chapters of the TweakGuides Tweaking Companion once again for details and links to relevant tools. The best way to guarantee stable voltage from a PSU is to buy a better-known quality brand, rather than relying on any generic PSUs which typically come installed in cases.

The next section looks at Catalyst installation and setup.